The long-term objective of the research is to develop and fabricate an instrument that can facilitate the discovery of new drugs via high throughput screening (HTS). ECIS (electric cell-substrate impedance sensing) is a technology developed by Applied BioPhysics to study the behavior of cultured cells in real time. Instruments manufactured by the company currently find use in over 150 laboratories world wide to measure such fundamental cell properties as permeability of cell monolayers, cell migration and cell-extra cellular matrix interactions. The ECIS instrumentation had been limited to low throughput research endeavors where a maximum of 16 individual cell cultures could be monitored. Phase I research culminated in the development and fabrication of the first 96 well version of ECIS. This instrument is limited to measurements of simple impedance and has a throughput restricted to a single 96 well plate. In spite of these limitations, the ECIS 9600 instrument is now being successfully marketed primarily to academic laboratories. The objective of the Phase II research is to build upon the success of Phase I and create a truly high throughput ECIS system. The new instrument will be capable of monitoring the complex impedance of ECIS culture wells over a broad spectrum of AC frequencies. Custom electronics will accommodate rapid data acquisition of large numbers of 96 well plates permitting thousands of individual wells to be screened. The instrument will capitalize upon the power of monitoring complex impedance and will be tailored for two important cell-based assays. One of these assays will involve measurement of cell migration based on an automated ECIS-based wound-healing assay. The other will monitor changes in barrier function of cell layers. None of these important measurements can presently be accomplished in a high throughput assay. The achievement of these goals will involve several steps: "development and testing the necessary electronics," design and testing of affordable consumable arrays specifically tailored for each assay, "production of custom software to run assays and manage the large resulting data files, "interfacing the ECIS instrumentation with standard robotic plate handlers. Once a complete prototype instrument has been fabricated, we will establish two beta test sites where the instrumentation and its software will be thoroughly evaluated and changes implemented to yield the final production unit. In Phase III, the instrument will be used in HTS assays in the pharmaceutical industry, where literally tens of thousands of test compounds will be evaluated in the search for modern therapeutic drugs.